1. Field of the Invention
This invention relates to turbines and, more particularly, to turbines for use in water turbines, steam turbines and gas turbines.
2. Description of the Related Art
U.S. Pat. Nos. 5,385,446 and 5,624,235 disclose steam turbines in which working fluid flows in an axial direction through multi-staged stator blades and turbine blades. In these turbines, there are spacings between an inner wall of a turbine housing and outer peripheries of the turbine blades, and unused working fluid escapes through those spacings without impinging upon the turbine blades. Thus, the turbine becomes low in efficiency, large in size and high in manufacturing costs U.S. Pat. No. 5,071,312 discloses a turbine having a rotor which is a disc with blades priojecting axially from its face working with rotor blades on a disc-like stator. In this turbine, the rotor blades have their rear surfaces impinging upon the radially flowing working fluid and, thus, a reaction torque is applied to the rotor so that its output power is reduced. Therefore, it is difficult to improve the operating efficiency of the above turbine.
JP-81,502 discloses a turbine having a rotor with its outer periphery formed with an annular partition wall to define a peripheral passage. In this turbine, the peripheral passage incorporates therein a plurality of circumferentially spaced blades which intersect the flow of the working fluid at right angles. When the working fluid impinges upon the blades during rotation of the rotor, turbulent flows are created in the peripheral passage, and the working fluid can not smoothly flow through the peripheral passage. When the rotor speed increases, a strong fluid reaction wall in unity with the rotor blades is created in the peripheral passage thereby increasing a back pressure, and the turbine operates at an extremely lowered efficiency. Further, rotor blades are weak in strength and, therefore, the turbine becomes large in size, thereby increasing the manufacturing costs.
It is therefore an object of the present invention to provide a turbine which can overcome the shortcomings encountered in the prior art.
It is another object of the present invention to provide a turbine which has a high operating efficiency, compact in structure, small in size and low in manufacturing costs.